Integrated transcriptome and metabolome analysis provides insights into anthocyanin biosynthesis in Cichorium intybus L.

Background: Chicory is a unique and nutritious vegetable crop. However, the molecular mechanisms underlying anthocyanin biosynthesis in chicory remain poorly understood. We combined transcriptomics and metabolomics analyses to explore the molecular basis of anthocyanin biosynthesis in red-budded (Z1) and yellow-budded (Z7) chicory.

Results: Integrated transcriptomics and metabolomics analyses were performed to investigate the molecular basis of anthocyanin biosynthesis in chicory. A total of 26 key structural genes, including F3'H, DFR, CHS, and ANS, were identified and enriched in pathways such as flavonoid and anthocyanin biosynthesis. Additionally, 29 transcription factors were identified, including 11 MYB, five bHLH, and two WD40 transcription factors, with seven MYB genes upregulated and four genes downregulated, indicating their roles in regulating anthocyanin biosynthesis. Notably, the MYB transcription factor, CI35997, which is homologous to RLL2A in lettuce, was predicted to positively regulate anthocyanin biosynthesis. Other transcription factors, such as AP2/ERF, bZIP, NAC, and Trihelix, have also been implicated. Metabolomics analysis revealed that cyanidin derivatives were the main contributors to the red coloration of chicory buds, with cyanidin-3-O-(6-O-malonyl)-glucoside being the most abundant. Furthermore, a competitive relationship between lignin and anthocyanin biosynthesis was observed, wherein the downregulation of lignin-related genes enhanced anthocyanin accumulation.

Conclusions: This study identified key structural genes and transcription factors that offer molecular-level insights into anthocyanin biosynthesis in chicory. These findings provide valuable guidance for genetic improvement of chicory and other crops with high anthocyanin content.